When dealing with most visual art, you're restricted to viewing the end product. If I go to the Louvre or the MOMA, I can look at the finished products but cannot see the process by which they were created. These paintings, for the most part, are "art", based solely on their end-state; and the fact that they are in a museum of art.
So what happens when you have a painting made by a machine put up in a gallery next to a painting done by a human being, and you can't tell which is which? A "Turing Test" of sorts. What if you hook the viewers up to an FMRI and see that both paintings generate an equivalent emotional response in the viewer?
If the machine-made painting is "not art" because it was made by a machine, what does that mean for human-made painting? Is it no longer art because it was indistinguishable from something that we've determined is non-art?
At that point, what is the definition of "art"? And the criteria for determining what is and is not art?
Do you remember that guy who had paint forced up his rectum as an enema, and then he stood over a canvas as is sprayed back out? This was considered art (by the artistic community). If that meets the standard for "art" then I'm willing to give a robot (and its creators and programmers) the benefit of the doubt.